Electropneumatic double control valve comprising a sealing arrangement

ABSTRACT

Electropneumatic double regulating valve for an air-operated vehicle brake system, which is disposed centrally on a wheel axle, equipped with two brakes, with a common relay valve housing ( 1 ), in which is integrated for each brake an assigned regulating valve unit, which comprises for valve actuation a control piston, which can be axially adjusted and is disposed inside an assigned control chamber ( 3   a   , 3   b ) and which is driven with a control pressure by way of an electromagnetic pilot valve assembly, housed in an adjacent pilot valve housing, for independent axial adjustment, whereby the pilot valve housing is connected detachably to the relay valve housing ( 1 ) by way of a sealing arrangement that lies in-between, whereby the sealing arrangement is designed as one-piece and comprises two sealing ring segments ( 5   a   , 5   b ), which are in essence ring-shaped and are assigned to one control chamber ( 3   a   , 3   b ) each and which are connected together by means of several footbridges ( 6   a  to  6   c ), which are molded on in-between and which are separated from each other in such a manner between the two sealing ring segments ( 5   a   , 5   b ) that an elastic deformation of the footbridges ( 6   a  to  6   c ) results in a defined compensation of the tolerance of the relative position of both sealing ring segments ( 5   a   , 5   b ) in the connecting plane between the pilot valve housing and the relay valve housing ( 1 ).

The present application is an International Patent Application No.PCT/EP02/04628, filed Apr. 26, 2002, designating the United States ofAmerica and published in German as WO 02/102635, the entire disclosureof which is incorporated herein by reference. Priority is claimed basedon Federal Republic of Germany Patent Application No. 101 20 324.1,filed Apr. 26, 2001.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to an electropneumatic double regulating valve foran air-operated vehicle brake system.

The electropneumatic double regulating valve of the present invention isdisposed centrally on a wheel axle, equipped with two brakes, with acommon relay valve housing, in which is integrated for each brake anassigned regulating valve unit, which comprises for valve actuation acontrol piston, which can be axially adjusted and is disposed inside anassigned control chamber and which is driven with a control pressure byway of an electromagnetic pilot valve assembly, housed in an adjacentpilot valve housing, for independent axial adjustment, whereby the pilotvalve housing is connected detachably to a relay valve housing by way ofa sealing arrangement that lies in-between. In particular the presentinvention relates to a special configuration of this sealingarrangement.

A generic regulating valve is installed inside an air brake system of avehicle, in order to correct a brake pressure in accordance with thedesired braking effect. For this purpose a brake line, issuing from theregulating valve, is usually connected to a brake cylinder on thevehicle wheel. Said brake cylinder produces the brake force, required tobrake the vehicle wheel, for a disk or drum brake attached to saidwheel. The desired pressure value for the electropneumatic regulatingvalve can be specified both electrically and pneumatically. However, thepneumatic drive is usually used only for safety in the case that theelectric drive fails.

Such an electropneumatic regulating valve is known from the DE 196 05562 A1. The regulating valve exhibits an internal control piston, whichhas a large area and is housed inside a control chamber, disposed in therelay valve housing. The control piston separates the control chamberfrom an opposing working chamber. On the side of the working chamber acoaxial hollow pin, which serves to actuate an adjacent valve seatassembly, is formed on the control piston. The valve seat assemblyswitches, by means of an axial adjustment of a spring-stressed valvetube, the compressed air flow between an external brake line connection,a feed pressure connection, as well as a venting port. The controlchamber is actuated by means of a pilot valve assembly with a controlpressure, which acts on a control piston. The pilot valve assemblycomprises here two electropneumatic pilot valves, which affect, by meansof a coordinated flow around the integrated electric coils, an increase,hold or decrease in the control pressure inside the control chamber,which produces a working pressure for the brake cylinder on the oppositeside of the control piston. The pilot valve housing is connecteddetachably to the relay valve housing by means of a sealing ring, whichseals the working chamber in the direction of the atmosphere.

In addition to the above described embodiment of an electropneumaticregulating valve with a single integrated regulating valve unit, thebackground art also discloses double regulating valves, wherein tworegulating valve units are integrated into a common relay valve housing.This configuration is usually used for rear axles of motor vehicles,where a central arrangement on the frame is possible. In this respectthe double regulating valve actuates both brakes, assigned to the wheelsof the wheel axles.

In casting the common relay valve housing and also the pilot valvehousing connected thereto, there is the problem that the exact relativeposition of both adjacent control chambers cannot be reliablyguaranteed. In addition to this casting-induced housing tolerance, thesealing rings that are used are also subject to a tolerance.Consequently the result can be an unfavorable chain of tolerances, sothat the tightness between the relay valve housing and the pilot valvehousing is not always guaranteed. In addition, individual sealing ringsare often forgotten during manual assembly so that the resulting cost ofreworking is high.

Therefore; an object of the present invention is to further improve anelectropneumatic double regulating valve of the above described kind tothe effect that a simple to assemble sealing arrangement is found thatguarantees a reliable seal between the relay valve housing and the pilotvalve housing.

The problem is solved starting from an electropneumatic doubleregulating valve disposed centrally on a wheel axle equipped with twobrakes, with a common relay valve housing containing a control pistonfor each brake, each control piston being axially adjustable and drivenwith a control pressure by way of an electromagnetic pilot valveassembly housed in an adjacent pilot valve housing, whereby the pilotvalve housing is connected detachably to the relay valve housing by wayof a sealing arrangement that lies in-between,

The problem is solved in one embodiment of the invention, by a one-piecesealing arrangement, comprising two sealing ring segments, which are inessence ring-shaped and are assigned to one control chamber each andwhich are connected together by means of several footbridges, which aremolded on in-between and which are separated from each other in such amanner between the two sealing ring segments that an elastic deformationof the footbridges results in a defined compensation of the tolerance ofthe relative position of both sealing ring segments in the connectingplane between the pilot valve housing and the relay valve housing.

An advantage of the inventive sealing arrangement lies in the fact that,owing to the individual sealing components being one piece, they cannotbe forgotten during assembly. In addition, the one piece design of thesealing arrangement offers ideal conditions for automating the assemblyprocess. The flexibility in spacing the two sealing ring segments makesit easy to compensate for the casting-induced tolerances at the relayvalve housing and/or the pilot valve housing. The invention makes itpossible to compensate for the tolerances with the elastically flexiblefootbridges. In this manner the tolerances can be balanced withouthardly any force.

According to another embodiment of the invention, at least one of thefootbridges is designed relatively rigid and at least one of thefootbridges, arranged separately on the opposite side, is designedrelatively elastic so that the tolerance is balanced by adjusting theangle of the two sealing ring segments with respect to each other. Theresult of the rigidly designed footbridge is an easy to manipulatesealing arrangement, which is relatively stable in its one-piece form,whereby the elastic footbridge compensates for the tolerance.

Preferably the footbridges are designed in the shape of an outwardlyoriented arch in order to facilitate the deformation. In addition, thefootbridges can be formed with a round to oval cross section in order toavoid twisting during deformation.

According to another embodiment of the invention, the two adjacentfootbridges can serve together with the neighboring arch members of thesealing ring segments to seal a pressure medium channel running betweenthe pilot valve housing and the relay valve housing. Such a pressuremedium channel can be provided, for example, to provide feed pressurefrom the feed pressure connection at the relay valve housing for thepilot valves, housed in the pilot valve housing. To seal this pressuremedium channel, there is no need to provide a separate sealing element.

To guarantee adequate shape stability for the sealing arrangement, thetwo sealing ring segments, made of an elastic material, and the rigidfootbridges can be provided with an internal reinforcing insert, made ofa rigid material, like steel, aluminum, or plastic.

Preferably the sealing ring segments comprise a main sealing segment,extending radially in the connecting plane between the pilot valvehousing and the relay valve housing, and an external radial sealingsegment for a static seal of the housing as well as an internal radialsealing segment for a dynamic seal of the control piston. In addition,in the area of the main sealing segment at least one point on theperiphery of the sealing ring segment can exhibit a passage for avalve-internal pressure medium channel, running between the relay valvehousing and the pilot valve housing. Such a passage can also be used asa holder for a pressure compensating element, integrated into thesealing arrangement. The pressure compensating element is provided tobalance the pressure with the atmosphere for valve-internal areas of thepilot valve housing that are not used as the pressure chamber.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a relay valve housing of a double regulatingvalve in accordance with an embodiment of the invention.

FIG. 2 is a top view of a sealing arrangement, used in the relay valvehousing, according to the embodiment of the invention in FIG. 1; and

FIG. 3 is a longitudinal view of the sealing arrangement, according tothe embodiment of the invention in FIG. 2.

DETAILED DESCRIPTION

According to FIG. 1, an electropneumatic double regulating valveincludes a relay valve housing 1, which is connected to a pilot valvehousing (not illustrated here). The contact surface of the pilot valvehousing is designed to correspond to the relay valve housing 1 along theline of a conventional half of the housing and is screwed by way ofdiverse boreholes 2 a–2 d to the relay valve housing 1. Inside the relayvalve housing 1 there are two axis-parallel control chambers 3 a, 3 b,in which there are control pistons (also not shown here in detail) toactuate the valve along the line of a pre-controlled seat valve. Thecontrol piston is actuated by way of a pilot valve assembly, which ishoused in the pilot valve housing, and which comprises individual,electrically switched solenoid valves. Between the two control chambers3 a and 3 b there are two pressure medium channels 4 a, 4 b, which runbetween the relay valve housing 1 and the pilot valve housing and whichserve to guide the valve-internal compressed air between the pilot valvehousing and the relay valve housing 1. In the face sided area of therelay valve housing 1, going around the two control chambers 3 a, 3 band the two valve-internal pressure medium channels 4 a, 4 b, there is asealing arrangement that enables a sealing connection between the relayvalve housing 1 and the pilot valve housing.

According to FIG. 2, this sealing arrangement is formed by two sealingring segments 5 a, 5 b, each of which is assigned to a control chamber(not illustrated here). Both sealing ring segments 5 a, 5 b areconnected together by means of three molded-on footbridges 6 a–6 c. Inthis respect the footbridge 6 a is designed relatively elastic, whereasthe two opposite, separately arranged footbridges 6 b and 6 c arerelatively rigid. As a consequence, the compensation for the tolerancestargeted with this sealing arrangement is possible by adjusting theangle of the two sealing ring segments 5 a, 5 b with respect to eachother. The two neighboring footbridges 6 b and 6 c serve together withthe adjacent arch members of the sealing ring segments 5 a and 5 b toseal the medium channel 4 b (not shown in this figure), which runsbetween the pilot valve housing and the relay valve housing. The otherpressure medium channel 4 a is sealed through the interaction of thefootbridges 6 a and 6 b in connection with the adjacent arch members ofthe sealing ring segments 5 a and 5 b. In the periphery of the sealingring segments 5 a, 5 b there are diverse passage 7 a, 7 b, in order toguarantee a sealed connection of the valve-internal pressure mediumchannels, running between the relay valve housing and the pilot valvehousing. A pressure compensating element 8 a, 8 b is cast into two suchpassages, in order to provide a protected pressure compensation with theatmosphere for valve-internal areas of the pilot valve housing that arenot used as the pressure chamber. Since the pressure compensatingelements are integrated into the sealing arrangement, there is no needfor a separate assembly in a corresponding housing segment.

As evident from FIG. 3, each sealing ring segment 5 a, 5 b comprises amain sealing segment 9, which extends radially in the connecting planebetween the pilot valve housing and the relay valve housing 1 and towhich is molded an external radial sealing segment 10 for a static sealof the housing as well as an internal radial sealing segment 11 for adynamic seal of the control piston. Furthermore, a reinforcing insert12, made of a rigid material, is cast into the sealing ring segments 5a, 5 b, in order to guarantee the shape stability of the sealingarrangement.

The foregoing disclosure has been set forth merely to illustrate theinvention and is not intended to be limiting. Since modifications of thedisclosed embodiments incorporating the spirit and substance of theinvention may occur to persons skilled in the art, the invention shouldbe construed to include everything within the scope of the appendedclaims and equivalents thereof. For example, the invention is inparticular not limited to the number and function of the passages,provided in the area of the sealing ring segments, for sealing thevarious valve-internal pressure medium channels, running next to the twocontrol chambers.

1. Electropneumatic double regulating valve for an air-operated vehicle brake system, which is disposed centrally on a wheel axle, equipped with two brakes, with a common relay valve housing, in which is integrated for each brake a respective regulating valve unit, which comprises for valve actuation a control piston, which can be axially adjusted and is disposed inside a respective control chamber and which is driven with a control pressure by way of an electromagnetic pilot valve assembly, housed in an adjacent pilot valve housing, for independent axial adjustment, whereby the pilot valve housing is connected detachably to the relay valve housing with a sealing arrangement that lies in-between, wherein the sealing arrangement is designed as one-piece and comprises two circular sealing ring segments which are connected together by a plurality of footbridges, which are molded in-between said two circular sealing ring segments and which are separated from each other in such a manner between the two sealing ring segments that an elastic deformation of the footbridges results in a defined compensation of a tolerance of a relative position of both sealing ring segments in a connecting plane between the pilot valve housing and the relay valve housing.
 2. Electropneumatic double regulating valve, as claimed in claim 1, wherein at least one footbridge on a first side of the sealing arrangement is designed relatively rigid and at least one footbridge, arranged separately on the an opposite side of the sealing arrangement, is designed relatively elastic so that the tolerance is balanced by adjusting the angle of the two sealing ring segments with respect to each other.
 3. Electropneumatic double regulating valve, as claimed in claim 2, wherein two adjacent footbridges serve together with the neighboring arch members of the sealing ring segments to seal a pressure medium channel between the pilot valve housing and the relay valve housing.
 4. Electropneumatic double regulating valve, as claimed in claim 3, wherein the two sealing ring segments, made of an elastic material, as well as the rigid footbridges are provided with an internal reinforcing insert, made of a rigid material.
 5. Electropneumatic double regulating valve, as claimed in claim 2, wherein the two sealing ring segments, made of an elastic material, as well as the rigid footbridges are provided with an internal reinforcing insert, made of a rigid material.
 6. Electropneumatic double regulating valve, as claimed in claim 5, wherein the reinforcing insert is made of steel, aluminum, brass or a rigid plastic.
 7. Electropneumatic double regulating valve, as claimed in claim 2, wherein the sealing ring segments comprise a main sealing segment, extending radially in the connecting plane between the pilot valve housing and the relay valve housing, which includes an external radial sealing segment for a static seal of the housing as well as an internal radial sealing segment for a dynamic seal of the control piston.
 8. Electropneumatic double regulating valve, as claimed in claim 7, wherein in the area of the main sealing segment at at least one point on the periphery of the sealing ring segment includes a passage to permit passage of a valve-internal pressure medium channel, running from the relay valve housing to the pilot valve housing.
 9. Electropneumatic double regulating valve, as claimed in claim 7, wherein in the area of the main sealing segment a pressure compensating element is placed on at least one point on the periphery of the sealing ring segment to provide a protected pressure compensation with the atmosphere for the areas of the pilot valve housing that are not used as the pressure chamber.
 10. Electropneumatic double regulating valve, as claimed in claim 1, wherein the plurality of footbridges have an outwardly oriented arch shape in order to facilitate the deformation.
 11. Electropneumatic double regulating valve, as claimed in claim 10, wherein two adjacent footbridges serve together with the neighboring arch members of the sealing ring segments to seal a pressure medium channel between the pilot valve housing and the relay valve housing.
 12. Electropneumatic double regulating valve, as claimed in claim 1, wherein the plurality of footbridges include one of a round and an oval cross section in order to avoid twisting during deformation.
 13. Electropneumatic double regulating valve, as claimed in claim 1, wherein two adjacent footbridges serve together with the neighboring arch members of the sealing ring segments to seal a pressure medium channel between the pilot valve housing and the relay valve housing.
 14. Electropneumatic double regulating valve, as claimed in claim 13, wherein the two sealing ring segments, made of an elastic material, as well as the rigid footbridges are provided with an internal reinforcing insert, made of a rigid material.
 15. Electropneumatic double regulating valve, as claimed in claim 1, wherein two adjacent footbridges serve together with the neighboring arch members of the sealing ring segments to seal a pressure medium channel between the pilot valve housing and the relay valve housing.
 16. Electropneumatic double regulating valve, as claimed in claim 1, wherein the two sealing ring segments, made of an elastic material, as well as the rigid footbridges are provided with an internal reinforcing insert, made of a rigid material.
 17. Electropneumatic double regulating valve, as claimed in claim 16, wherein the reinforcing insert is made of steel, aluminum, brass or a rigid plastic.
 18. Electropneumatic double regulating valve, as claimed in claim 1, wherein the sealing ring segments comprise a main sealing segment, extending radially in the connecting plane between the pilot valve housing and the relay valve housing, which includes an external radial sealing segment for a static seal of the housing as well as an internal radial sealing segment for a dynamic seal of the control piston.
 19. Electropneumatic double regulating valve, as claimed in claim 18, wherein in the area of the main sealing segment at at least one point on the periphery of the sealing ring segment includes a passage to permit passage of a valve-internal pressure medium channel, running from the relay valve housing to the pilot valve housing.
 20. Electropneumatic double regulating valve, as claimed in claim 18, wherein in the area of the main sealing segment a pressure compensating element is placed on at least one point on the periphery of the sealing ring segment to provide a protected pressure compensation with the atmosphere for the areas of the pilot valve housing that are not used as the pressure chamber.
 21. An electropneumatic double regulating valve for an air-operated vehicle brake system disposed centrally on a wheel axle equipped with two brakes, comprising: a common relay valve housing, including for each brake, a regulating valve unit and an axially adjustable control piston for valve actuation disposed inside a control chamber; and a common pilot valve housing connected detachably to the relay valve housing, including for each brake an electromagnetic pilot valve assembly which drives its respective control piston for independent axial adjustment, wherein a sealing arrangement is disposed between the relay valve housing and the pilot valve housing when connected to one another, and the sealing arrangement is one-piece and includes two circular sealing ring segments linked by a plurality of footbridges, the footbridges being deformable to compensate for a tolerance of a relative position of the sealing ring segments when the pilot valve housing and the relay valve housing are connected to one another.
 22. The electropneumatic double regulating valve of claim 21, wherein at least one footbridge on a first side of the sealing arrangement is more rigid than another of the plurality of footbridges disposed on an opposite side of the sealing arrangement, and the tolerance is compensated by adjusting the angle of the two sealing ring segments with respect to each other.
 23. The electropneumatic double regulating valve of claim 22, wherein a sealed pressure medium channel between the pilot valve housing and the relay valve housing is defined by two adjacent footbridges and the sealing ring segments between the two adjacent footbridges.
 24. The electropneumatic double regulating valve of claim 22, wherein the two sealing ring segments and footbridges are provided with a rigid internal reinforcing insert.
 25. The electropneumatic double regulating valve of claim 24, wherein the reinforcing insert is made from at least one of steel, aluminum, brass and a rigid plastic.
 26. The electropneumatic double regulating valve of claim 22, wherein the sealing ring segments each includes a double-walled seal arrangement wherein when the relay valve housing and the pilot valve housing are connected, an internal radial sealing segment seals its respective control chamber from an external radial sealing segment radially surrounding the internal radial sealing element.
 27. The electropneumatic double regulating valve of claim 26, wherein a valve-internal pressure medium channel from the relay valve housing to the pilot valve housing passes through at least one passage between the internal radial sealing segment and the external radial sealing segment.
 28. The electropneumatic double regulating valve of claim 26, wherein a pressure compensating element, which provides a protected pressure compensation with the atmosphere for non-pressurized areas of the pilot valve housing, passes between the internal radial sealing segment and the external radial sealing segment.
 29. The electropneumatic double regulating valve of claim 21, wherein the plurality of footbridges are curved away from a center of the sealing arrangement.
 30. The electropneumatic double regulating valve of claim 21, wherein the plurality of footbridges include one of a round and an oval cross section in order to avoid twisting during deformation.
 31. The electropneumatic double regulating valve of claim 21, wherein a sealed pressure medium channel between the pilot valve housing and the relay valve housing is defined by two adjacent footbridges and the sealing ring segments between the two adjacent footbridges.
 32. The electropneumatic double regulating valve of claim 21, wherein the two sealing ring segments and footbridges are provided with a rigid internal reinforcing insert.
 33. The electropneumatic double regulating valve of claim 32, wherein the reinforcing insert is made from at least one of steel, aluminum, brass and a rigid plastic.
 34. The electropneumatic double regulating valve of claim 21, wherein the sealing ring segments each includes a double-walled seal arrangement wherein when the relay valve housing and the pilot valve housing are connected, an internal radial sealing segment seals its respective control chamber from an external radial sealing segment radially surrounding the internal radial sealing element.
 35. The electropneumatic double regulating valve of claim 34, wherein a valve-internal pressure medium channel from the relay valve housing to the pilot valve housing passes through at least one passage between the internal radial sealing segment and the external radial sealing segment.
 36. The electropneumatic double regulating valve of claim 34, wherein a pressure compensating element, which provides a protected pressure compensation with the atmosphere for non-pressurized areas of the pilot valve housing, passes between the internal radial sealing segment and the external radial sealing segment. 